Ball Joint And Bearing Shell

ABSTRACT

A bail joint for a wheel suspension in a vehicle, said bail joint including a bearing shell ( 3 ), a bail ( 2 ) and housing ( 4 ). The ball is supported in the bearing shell; said bearing shell ( 3 ) being subdivided into lip elements ( 9 ) by slots ( 8 ). The slots ( 8 ) are arranged in the bearing shell ( 3 ) from its middle part and up to its upper rim. The lip elements ( 9 ) may be bent outwards at a compression groove ( 10 ) to admit the bail ( 2 ) when it is introduced into the shell.

FIELD OF THE INVENTION

The present invention relates to a ball and socket joint for wheel suspension units in vehicles.

TECHNICAL BACKGROUND

Ball joints utilised in the steering gear and wheel suspension in cars normally comprise a shell and a ball mounted in this. The function of the shell is as a bearing in the joint and to distribute the lubricant onto the surface of the ball. This is particularly important when the ball lacks other corrosion inhibiting measures. The shell shall also enable preloading of the ball to prevent slip in the connection. In order to mount the ball in a single piece shell, it is necessary to allow the opening at the open end of the shell to be expanded to the same size as the diameter of the ball. Normally this is achieved by splitting this end with 6-8 slots down to the centre of the shell forming lip elements, and there providing a thinning of the shell to enable the lips to be turned outwards, se FIGS. 1 and 2.

The disadvantage of this prior art solution is that all measures mentioned above contribute to reduce the active load bearing area of the shell and thus reduce the load carrying potential at a given diameter. Due to room restrictions it is often necessary to use a ball as small as possible in the joint, which is contradictory of the design of the shells.

SHORT SUMMARY OF THE INVENTION

Thus, it is an object of the present invention to provide a shell for systems in which the primary load is in a mainly horizontal direction (75-100° on the ball stud); the shell providing an efficient distribution of lubricant over the ball; the shell being made in a single piece; being of a smaller size and having increased load carrying capacity compared with prior art shells.

This is achieved in a shell as defined in the independent claim. Advantageous embodiments of the shell appear from the dependent claims.

SHORT DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in detail in reference to the appended drawings, in which:

FIG. 1 shows a section though a prior art ball joint,

FIG. 2 shows a detail of a prior art ball joint which illustrates how a ball is mounted in a shell,

FIG. 3 shows the shell of the invention, in sectional and top views,

FIG. 4 shows a detail of the inventive shell,

FIG. 5 shows a detail of the inventive shell.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a prior art ball joint (1). The ball joint comprises a ball (2) arranged in a control arm (4) by being in mesh with a cavity with an associated shell (3). The ball joint (1) further provides a connection between the control arm (4) and a wheel housing (7). The cavity with the ball and shell is protected with rubber bellows for preventing the intrusion of extraneous matter and dirt impairing the freedom of movement. The ball joint is lubricated with grease (5) or another lubricant which is distributed around the ball by 6-8 slots (8) in the shell (3). The slots (8) have another function in addition to the distribution of lubricant (5). The slots subdivide the shells in lip elements (9) enabling the shell to be opened to admit the ball (2) as shown in FIG. 2. The expansion of the opening is made possible by the lip elements being tapered at the centre of the shell in a compression groove (10) providing weakened areas allowing the lip elements 9 to be bent outwards.

The inventive shell has the same function as the prior art shell shown in FIGS. 1 and 2, but it is designed to increase the load carrying capacity of the ball joint (1) by a given diameter. According to the invention, two slots (8) are provided in the shell. In order for the slots to provide a good lubricating action, they are designed as arched incisions or spiral slots on opposite sides of the shell, extending mainly diagonally around the shell from the opening to beneath the centre of the shell. Accordingly, the slots are arranged 180° from each other, and 90° on the main loading direction, as shown in FIG. 3.

Due to the arrangement of the slots, the compression groove (10) is relocated from the centre, which is the most loaded area, with about 3.5 mm, as shown in FIG. 4

In addition, the shell is designed in a new way. The wall of the shell has decreasing thickness from the centre towards the opening of the shell so that the horizontally projected thickness (t1, t2) is constant in size up to the rim of the shell (see FIG. 5). This means that the effective thickness (t) is decreasing. This design provides a specific pressure in the active surface which is as homogeneous as possible, and thus the shell (2) may stand a larger load.

The characterizing features mentioned above will significantly improve the load carrying capacity of the shell at a given diameter of the ball, or when room restrictions dictates, to decrease its dimensions. 

1. A ball joint for wheel suspension in vehicles including a shell (3), a ball (2) and a housing (4), in which the ball is mounted in the shell and the shell (3) is sub-divided into lip elements (9) by slots (8) arranged in the shell (3) from the middle part of the shell (3) and up to its upper rim, the lip elements (9) may be bent outward in a compression groove (10) to make room for the ball (2), characterized in that at least two slots (8) are arranged in the shell (3) as arched incisions or spiral slots on opposite sides of the shell (3), and which is arranged to extend mainly diagonally around parts of the shell (3) from the rim of the shell to the area at the centre line of the shell.
 2. A ball joint as claimed in claim 1, characterized in that the shell (3) includes two slots (8), the slots (2) being arranged 180° from each other and 90° on the direction of main loading.
 3. A ball joint as claimed in claim 1, characterized in that the compression groove (10) is displaced beneath the centre of the shell (3).
 4. A ball joint as claimed in claim 1, characterized in that the wall thickness of the shell (3) is decreasing from the centre and up towards the rim of the lip elements (9), such that its horizontally projected thickness is constant and the relative thickness is decreasing.
 5. A ball joint as claimed in claim 1, characterized in that the housing (4) is an integrated part of a control arm (4).
 6. A shell (3) for a ball joint (1) for wheel suspension in vehicles, the shell (3) being sub-divided in lip elements (9) by slots (8) provided in the shell (3) from the centre part of the shell (3) and up to its upper rim, the lip elements (9) can be bent outward in a compression groove (10) to admit the ball (2), characterized in at least two slots (8) arranged in the shell (3) as arched incisions or spiral slots on opposite sides of the shell (3), and arranged to extend mainly diagonally around parts of the shell (3) from the rim of the shell to the area at the centre line of the shell.
 7. A shell as claimed in claim 6, characterized in that it includes two slots (8) which is arranged 180° from each other and 90° on the direction of main loading. 